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Tsai KK, Bae BI, Hsu CC, Cheng LH, Shaked Y. Oncogenic ASPM Is a Regulatory Hub of Developmental and Stemness Signaling in Cancers. Cancer Res 2023; 83:2993-3000. [PMID: 37384617 PMCID: PMC10502471 DOI: 10.1158/0008-5472.can-23-0158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 01/27/2023] [Accepted: 06/26/2023] [Indexed: 07/01/2023]
Abstract
Despite recent advances in molecularly targeted therapies and immunotherapies, the effective treatment of advanced-stage cancers remains a largely unmet clinical need. Identifying driver mechanisms of cancer aggressiveness can lay the groundwork for the development of breakthrough therapeutic strategies. Assembly factor for spindle microtubules (ASPM) was initially identified as a centrosomal protein that regulates neurogenesis and brain size. Mounting evidence has demonstrated the pleiotropic roles of ASPM in mitosis, cell-cycle progression, and DNA double-strand breaks (DSB) repair. Recently, the exon 18-preserved isoform 1 of ASPM has emerged as a critical regulator of cancer stemness and aggressiveness in various malignant tumor types. Here, we describe the domain compositions of ASPM and its transcript variants and overview their expression patterns and prognostic significance in cancers. A summary is provided of recent progress in the molecular elucidation of ASPM as a regulatory hub of development- and stemness-associated signaling pathways, such as the Wnt, Hedgehog, and Notch pathways, and of DNA DSB repair in cancer cells. The review emphasizes the potential utility of ASPM as a cancer-agnostic and pathway-informed prognostic biomarker and therapeutic target.
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Affiliation(s)
- Kelvin K. Tsai
- Laboratory of Advanced Molecular Therapeutics, Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Division of Gastroenterology, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
- TMU Research Center of Cancer Translational Medicine, Taipei Medical University, Taipei, Taiwan
| | - Byoung-Il Bae
- Department of Neuroscience, University of Connecticut School of Medicine, Farmington, Connecticut
| | - Chung-Chi Hsu
- School of Medicine, College of Medicine, I-Shou University, Kaohsiung City, Taiwan
| | - Li-Hsin Cheng
- Laboratory of Advanced Molecular Therapeutics, Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Yuval Shaked
- Department of Cell Biology and Cancer Science, Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, Haifa, Israel
- Technion Integrated Cancer Center, Technion – Israel Institute of Technology, Haifa, Israel
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2
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Nicastro G, Abis G, Klein P, Esteban-Serna S, Gallagher C, Chaves-Arquero B, Cai Y, Figueiredo AM, Martin SR, Patani R, Taylor IA, Ramos A. Direct m6A recognition by IMP1 underlays an alternative model of target selection for non-canonical methyl-readers. Nucleic Acids Res 2023; 51:8774-8786. [PMID: 37377445 PMCID: PMC10484666 DOI: 10.1093/nar/gkad534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 06/02/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
m6A methylation provides an essential layer of regulation in organismal development, and is aberrant in a range of cancers and neuro-pathologies. The information encoded by m6A methylation is integrated into existing RNA regulatory networks by RNA binding proteins that recognise methylated sites, the m6A readers. m6A readers include a well-characterised class of dedicated proteins, the YTH proteins, as well as a broader group of multi-functional regulators where recognition of m6A is only partially understood. Molecular insight in this recognition is essential to build a mechanistic understanding of global m6A regulation. In this study, we show that the reader IMP1 recognises the m6A using a dedicated hydrophobic platform that assembles on the methyl moiety, creating a stable high-affinity interaction. This recognition is conserved across evolution and independent from the underlying sequence context but is layered upon the strong sequence specificity of IMP1 for GGAC RNA. This leads us to propose a concept for m6A regulation where methylation plays a context-dependent role in the recognition of selected IMP1 targets that is dependent on the cellular concentration of available IMP1, differing from that observed for the YTH proteins.
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Affiliation(s)
- Giuseppe Nicastro
- Macromolecular Structure Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Giancarlo Abis
- Division of Biosciences, Institute of Structural and Molecular Biology, University College London, London, UK
| | - Pierre Klein
- Division of Biosciences, Institute of Structural and Molecular Biology, University College London, London, UK
| | - Sofia Esteban-Serna
- Division of Biosciences, Institute of Structural and Molecular Biology, University College London, London, UK
| | - Christopher Gallagher
- Division of Biosciences, Institute of Structural and Molecular Biology, University College London, London, UK
| | - Belen Chaves-Arquero
- Division of Biosciences, Institute of Structural and Molecular Biology, University College London, London, UK
| | - Yuyang Cai
- Division of Biosciences, Institute of Structural and Molecular Biology, University College London, London, UK
| | - Angelo Miguel Figueiredo
- Division of Biosciences, Institute of Structural and Molecular Biology, University College London, London, UK
| | - Stephen R Martin
- Structural Biology Technology Platform, The Francis Crick Institute, 1 Midland Rd, London NW1 1AT, UK
| | - Rickie Patani
- Human Stem Cells and Neurodegeneration Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Ian A Taylor
- Macromolecular Structure Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Andres Ramos
- Division of Biosciences, Institute of Structural and Molecular Biology, University College London, London, UK
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3
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Hovey L, Fowler CA, Mahling R, Lin Z, Miller MS, Marx DC, Yoder JB, Kim EH, Tefft KM, Waite BC, Feldkamp MD, Yu L, Shea MA. Calcium triggers reversal of calmodulin on nested anti-parallel sites in the IQ motif of the neuronal voltage-dependent sodium channel Na V1.2. Biophys Chem 2017; 224:1-19. [PMID: 28343066 PMCID: PMC5503752 DOI: 10.1016/j.bpc.2017.02.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 02/23/2017] [Accepted: 02/23/2017] [Indexed: 01/26/2023]
Abstract
Several members of the voltage-gated sodium channel family are regulated by calmodulin (CaM) and ionic calcium. The neuronal voltage-gated sodium channel NaV1.2 contains binding sites for both apo (calcium-depleted) and calcium-saturated CaM. We have determined equilibrium dissociation constants for rat NaV1.2 IQ motif [IQRAYRRYLLK] binding to apo CaM (~3nM) and (Ca2+)4-CaM (~85nM), showing that apo CaM binding is favored by 30-fold. For both apo and (Ca2+)4-CaM, NMR demonstrated that NaV1.2 IQ motif peptide (NaV1.2IQp) exclusively made contacts with C-domain residues of CaM (CaMC). To understand how calcium triggers conformational change at the CaM-IQ interface, we determined a solution structure (2M5E.pdb) of (Ca2+)2-CaMC bound to NaV1.2IQp. The polarity of (Ca2+)2-CaMC relative to the IQ motif was opposite to that seen in apo CaMC-Nav1.2IQp (2KXW), revealing that CaMC recognizes nested, anti-parallel sites in Nav1.2IQp. Reversal of CaM may require transient release from the IQ motif during calcium binding, and facilitate a re-orientation of CaMN allowing interactions with non-IQ NaV1.2 residues or auxiliary regulatory proteins interacting in the vicinity of the IQ motif.
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Affiliation(s)
- Liam Hovey
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - C Andrew Fowler
- NMR Facility, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 52242-1109 Iowa City, United States
| | - Ryan Mahling
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Zesen Lin
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Mark Stephen Miller
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Dagan C Marx
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Jesse B Yoder
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Elaine H Kim
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Kristin M Tefft
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Brett C Waite
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Michael D Feldkamp
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Liping Yu
- NMR Facility, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 52242-1109 Iowa City, United States
| | - Madeline A Shea
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States.
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4
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Self-organization of actin networks by a monomeric myosin. Proc Natl Acad Sci U S A 2016; 113:E8387-E8395. [PMID: 27956608 DOI: 10.1073/pnas.1612719113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The organization of actomyosin networks lies at the center of many types of cellular motility, including cell polarization and collective cell migration during development and morphogenesis. Myosin-IXa is critically involved in these processes. Using total internal reflection fluorescence microscopy, we resolved actin bundles assembled by myosin-IXa. Electron microscopic data revealed that the bundles consisted of highly ordered lattices with parallel actin polarity. The myosin-IXa motor domains aligned across the network, forming cross-links at a repeat distance of precisely 36 nm, matching the helical repeat of actin. Single-particle image processing resolved three distinct conformations of myosin-IXa in the absence of nucleotide. Using cross-correlation of a modeled actomyosin crystal structure, we identified sites of additional mass, which can only be accounted for by the large insert in loop 2 exclusively found in the motor domain of class IX myosins. We show that the large insert in loop 2 binds calmodulin and creates two coordinated actin-binding sites that constrain the actomyosin interactions generating the actin lattices. The actin lattices introduce orientated tracks at specific sites in the cell, which might install platforms allowing Rho-GTPase-activating protein (RhoGAP) activity to be focused at a definite locus. In addition, the lattices might introduce a myosin-related, force-sensing mechanism into the cytoskeleton in cell polarization and collective cell migration.
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5
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Ben-Johny M, Yue DN, Yue DT. Detecting stoichiometry of macromolecular complexes in live cells using FRET. Nat Commun 2016; 7:13709. [PMID: 27922011 PMCID: PMC5150656 DOI: 10.1038/ncomms13709] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 10/25/2016] [Indexed: 11/10/2022] Open
Abstract
The stoichiometry of macromolecular interactions is fundamental to cellular signalling yet challenging to detect from living cells. Fluorescence resonance energy transfer (FRET) is a powerful phenomenon for characterizing close-range interactions whereby a donor fluorophore transfers energy to a closely juxtaposed acceptor. Recognizing that FRET measured from the acceptor's perspective reports a related but distinct quantity versus the donor, we utilize the ratiometric comparison of the two to obtain the stoichiometry of a complex. Applying this principle to the long-standing controversy of calmodulin binding to ion channels, we find a surprising Ca2+-induced switch in calmodulin stoichiometry with Ca2+ channels—one calmodulin binds at basal cytosolic Ca2+ levels while two calmodulins interact following Ca2+ elevation. This feature is curiously absent for the related Na channels, also potently regulated by calmodulin. Overall, our assay adds to a burgeoning toolkit to pursue quantitative biochemistry of dynamic signalling complexes in living cells. Measuring the in vivo stoichiometry of protein-protein interactions is challenging. Here the authors take a FRET-based approach, quantifying stoichiometry based on ratiometric comparison of donor and acceptor fluorescence, and apply their method to report on a Ca2+-induced switch in calmodulin binding to Ca2+ ion channels.
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Affiliation(s)
- Manu Ben-Johny
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - Daniel N Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
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6
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Abstract
The myosin holoenzyme is a multimeric protein complex consisting of heavy chains and light chains. Myosin light chains are calmodulin family members which are crucially involved in the mechanoenzymatic function of the myosin holoenzyme. This review examines the diversity of light chains within the myosin superfamily, discusses interactions between the light chain and the myosin heavy chain as well as regulatory and structural functions of the light chain as a subunit of the myosin holoenzyme. It covers aspects of the myosin light chain in the localization of the myosin holoenzyme, protein-protein interactions and light chain binding to non-myosin binding partners. Finally, this review challenges the dogma that myosin regulatory and essential light chain exclusively associate with conventional myosin heavy chains while unconventional myosin heavy chains usually associate with calmodulin.
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Affiliation(s)
- Sarah M Heissler
- a Laboratory of Molecular Physiology; National Heart, Lung, and Blood Institute; National Institutes of Health ; Bethesda , MD USA
| | - James R Sellers
- a Laboratory of Molecular Physiology; National Heart, Lung, and Blood Institute; National Institutes of Health ; Bethesda , MD USA
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7
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Abstract
The ability to coordinate the timing of motor protein activation lies at the center of a wide range of cellular motile processes including endocytosis, cell division, and cancer cell migration. We show that calcium dramatically alters the conformation and activity of the myosin-VI motor implicated in pivotal steps of these processes. We resolved the change in motor conformation and in structural flexibility using single particle analysis of electron microscopic data and identified interacting domains using fluorescence spectroscopy. We discovered that calcium binding to calmodulin increases the binding affinity by a factor of 2,500 for a bipartite binding site on myosin-VI. The ability of calcium-calmodulin to seek out and bridge between binding site components directs a major rearrangement of the motor from a compact dormant state into a cargo binding primed state that is nonmotile. The lack of motility at high calcium is due to calmodulin switching to a higher affinity binding site, which leaves the original IQ-motif exposed, thereby destabilizing the lever arm. The return to low calcium can either restabilize the lever arm, required for translocating the cargo-bound motors toward the center of the cell, or refold the cargo-free motors into an inactive state ready for the next cellular calcium flux.
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8
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Wafer LN, Tzul FO, Pandharipande PP, McCallum SA, Makhatadze GI. Structural and thermodynamic characterization of the recognition of the S100-binding peptides TRTK12 and p53 by calmodulin. Protein Sci 2014; 23:1247-61. [PMID: 24947426 DOI: 10.1002/pro.2506] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 06/14/2014] [Accepted: 06/17/2014] [Indexed: 11/07/2022]
Abstract
Calmodulin (CaM) is a multifunctional messenger protein that activates a wide variety of signaling pathways in eukaryotic cells in a calcium-dependent manner. CaM has been proposed to be functionally distinct from the S100 proteins, a related family of eukaryotic calcium-binding proteins. Previously, it was demonstrated that peptides derived from the actin-capping protein, TRTK12, and the tumor-suppressor protein, p53, interact with multiple members of the S100 proteins. To test the specificity of these peptides, they were screened using isothermal titration calorimetry against 16 members of the human S100 protein family, as well as CaM, which served as a negative control. Interestingly, both the TRTK12 and p53 peptides were found to interact with CaM. These interactions were further confirmed by both fluorescence and nuclear magnetic resonance spectroscopies. These peptides have distinct sequences from the known CaM target sequences. The TRTK12 peptide was found to independently interact with both CaM domains and bind with a stoichiometry of 2:1 and dissociations constants Kd,C-term = 2 ± 1 µM and Kd,N-term = 14 ± 1 µM. In contrast, the p53 peptide was found to interact only with the C-terminal domain of CaM, Kd,C-term = 2 ± 1 µM, 25°C. Using NMR spectroscopy, the locations of the peptide binding sites were mapped onto the structure of CaM. The binding sites for both peptides were found to overlap with the binding interface for previously identified targets on both domains of CaM. This study demonstrates the plasticity of CaM in target binding and may suggest a possible overlap in target specificity between CaM and the S100 proteins.
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Affiliation(s)
- Lucas N Wafer
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York, 12180; Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, 12180
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9
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Calmodulin regulates dimerization, motility, and lipid binding of Leishmania myosin XXI. Proc Natl Acad Sci U S A 2013; 111:E227-36. [PMID: 24379364 DOI: 10.1073/pnas.1319285110] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Myosin XXI is the only myosin expressed in Leishmania parasites. Although it is assumed that it performs a variety of motile functions, the motor's oligomerization states, cargo-binding, and motility are unknown. Here we show that binding of a single calmodulin causes the motor to adopt a monomeric state and to move actin filaments. In the absence of calmodulin, nonmotile dimers that cross-linked actin filaments were formed. Unexpectedly, structural analysis revealed that the dimerization domains include the calmodulin-binding neck region, essential for the generation of force and movement in myosins. Furthermore, monomeric myosin XXI bound to mixed liposomes, whereas the dimers did not. Lipid-binding sections overlapped with the dimerization domains, but also included a phox-homology domain in the converter region. We propose a mechanism of myosin regulation where dimerization, motility, and lipid binding are regulated by calmodulin. Although myosin-XXI dimers might act as nonmotile actin cross-linkers, the calmodulin-binding monomers might transport lipid cargo in the parasite.
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10
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Abstract
Almost all of the elementary steps in a biochemical reaction scheme are either unimolecular or bimolecular processes that frequently occur on sub-second, often sub-millisecond, time scales. The traditional approach in kinetic studies is to mix two or more reagents and monitor the changes in concentrations with time. Conventional spectrophotometers cannot generally be used to study reactions that are complete within less than about 20 s, as it takes that amount of time to manually mix the reagents and activate the instrument. Rapid mixing techniques, which generally achieve mixing in less than 2 ms, overcome this limitation. This chapter is concerned with the use of these techniques in the study of reactions which reach equilibrium; the application of these methods to the study of enzyme kinetics is described in several excellent texts (Cornish-Bowden, Fundamentals of enzyme kinetics. Portland Press, 1995; Gutfreund, Kinetics for the life sciences. Receptors, transmitters and catalysis. Cambridge University Press, 1995).There are various ways to monitor changes in concentration of reactants, intermediates and products after mixing, but the most common way is to use changes in optical signals (absorbance or fluorescence) which often accompany reactions. Although absorbance can sometimes be used, fluorescence is often preferred because of its greater sensitivity, particularly in monitoring conformational changes. Such methods are continuous with good time resolution but they seldom permit the direct determination of the concentrations of individual species. Alternatively, samples may be taken from the reaction volume, mixed with a chemical quenching agent to stop the reaction, and their contents assessed by techniques such as HPLC. These methods can directly determine the concentrations of different species, but are discontinuous and have a limited time resolution.
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Affiliation(s)
- Stephen R Martin
- Division of Physical Biochemistry, MRC National Institute for Medical Research, London, UK
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11
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Xu XL, Ma W, Zhu YB, Wang C, Wang BY, An N, An L, Liu Y, Wu ZH, Tian JH. The microtubule-associated protein ASPM regulates spindle assembly and meiotic progression in mouse oocytes. PLoS One 2012; 7:e49303. [PMID: 23152892 PMCID: PMC3496685 DOI: 10.1371/journal.pone.0049303] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 10/08/2012] [Indexed: 11/19/2022] Open
Abstract
The microtubule-associated protein ASPM (abnormal spindle-like microcephaly-associated) plays an important role in spindle organization and cell division in mitosis and meiosis in lower animals, but its function in mouse oocyte meiosis has not been investigated. In this study, we characterized the localization and expression dynamics of ASPM during mouse oocyte meiotic maturation and analyzed the effects of the downregulation of ASPM expression on meiotic spindle assembly and meiotic progression. Immunofluorescence analysis showed that ASPM localized to the entire spindle at metaphase I (MI) and metaphase II (MII), colocalizing with the spindle microtubule protein acetylated tubulin (Ac-tubulin). In taxol-treated oocytes, ASPM colocalized with Ac-tubulin on the excessively polymerized microtubule fibers of enlarged spindles and the numerous asters in the cytoplasm. Nocodazole treatment induced the gradual disassembly of microtubule fibers, during which ASPM remained colocalized with the dynamic Ac-tubulin. The downregulation of ASPM expression by a gene-specific morpholino resulted in an abnormal meiotic spindle and inhibited meiotic progression; most of the treated oocytes were blocked in the MI stage with elongated meiotic spindles. Furthermore, coimmunoprecipitation combined with mass spectrometry and western blot analysis revealed that ASPM interacted with calmodulin in MI oocytes and that these proteins colocalized at the spindle. Our results provide strong evidence that ASPM plays a critical role in meiotic spindle assembly and meiotic progression in mouse oocytes.
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Affiliation(s)
- Xiao-Ling Xu
- Institute of Animal Husbandry and Veterinary Medicine, Beijing Municipal Academy of Agriculture and Forestry Sciences, Beijing, China
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Sciences and Technology, China Agricultural University, Beijing, China
| | - Wei Ma
- Department of Histology and Embryology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Yu-Bo Zhu
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Sciences and Technology, China Agricultural University, Beijing, China
| | - Chao Wang
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Sciences and Technology, China Agricultural University, Beijing, China
| | - Bing-Yuan Wang
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Sciences and Technology, China Agricultural University, Beijing, China
| | - Na An
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Sciences and Technology, China Agricultural University, Beijing, China
| | - Lei An
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Sciences and Technology, China Agricultural University, Beijing, China
| | - Yan Liu
- Institute of Animal Husbandry and Veterinary Medicine, Beijing Municipal Academy of Agriculture and Forestry Sciences, Beijing, China
| | - Zhong-Hong Wu
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Sciences and Technology, China Agricultural University, Beijing, China
| | - Jian-Hui Tian
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Sciences and Technology, China Agricultural University, Beijing, China
- * E-mail:
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12
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Black DJ, Persechini A. In calmodulin-IQ domain complexes, the Ca(2+)-free and Ca(2+)-bound forms of the calmodulin C-lobe direct the N-lobe to different binding sites. Biochemistry 2011; 50:10061-8. [PMID: 21999573 DOI: 10.1021/bi201300v] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have investigated the roles played by the calmodulin (CaM) N- and C-lobes in establishing the conformations of CaM-IQ domain complexes in different Ca(2+)-free and Ca(2+)-bound states. Our results indicate a dominant role for the C-lobe in these complexes. When the C-lobe is Ca(2+)-free, it directs the N-lobe to a binding site within the IQ domain consensus sequence. It appears that the N-lobe must be Ca(2+)-free to interact productively with this site. When the C-lobe is Ca(2+)-bound, it directs the N-lobe to a site upstream of the consensus sequence, and it appears that the N-lobe must be Ca(2+)-bound to interact productively with this site. A model for switching in CaM-IQ domain complexes is presented in which the N-lobe adopts bound and extended positions that depend on the status of the Ca(2+)-binding sites in each CaM lobe and the compositions of the two N-lobe binding sites. Ca(2+)-dependent changes in the conformation of the bound C-lobe that appear to be responsible for directed N-lobe binding are also identified. Changes in the equilibria between extended and bound N-lobe positions may control bridging interactions in which the extended N-lobe is bound to another CaM-binding domain. Ca(2+)-dependent control of bridging interactions with CaM has been implicated in the regulation of ion channel and unconventional myosin activities.
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Affiliation(s)
- D J Black
- Division of Molecular Biology and Biochemistry, University of Missouri, Kansas City, Missouri 64110-2499, USA
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13
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Crawley SW, Liburd J, Shaw K, Jung Y, Smith SP, Côté GP. Identification of calmodulin and MlcC as light chains for Dictyostelium myosin-I isozymes. Biochemistry 2011; 50:6579-88. [PMID: 21671662 DOI: 10.1021/bi2007178] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Dictyostelium discoideum express seven single-headed myosin-I isozymes (MyoA-MyoE and MyoK) that drive motile processes at the cell membrane. The light chains for MyoA and MyoE were identified by expressing Flag-tagged constructs consisting of the motor domain and the two IQ motifs in the neck region in Dictyostelium. The MyoA and MyoE constructs both copurified with calmodulin. Isothermal titration calorimetry (ITC) showed that apo-calmodulin bound to peptides corresponding to the MyoA and MyoE IQ motifs with micromolar affinity. In the presence of calcium, calmodulin cross-linked two IQ motif peptides, with one domain binding with nanomolar affinity and the other with micromolar affinity. The IQ motifs were required for the actin-activated MgATPase activity of MyoA but not MyoE; however, neither myosin exhibited calcium-dependent activity. A Flag-tagged construct consisting of the MyoC motor domain and the three IQ motifs in the adjacent neck region bound a novel 8.6 kDa two EF-hand protein named MlcC, for myosin light chain for MyoC. MlcC is most similar to the C-terminal domain of calmodulin but does not bind calcium. ITC studies showed that MlcC binds IQ1 and IQ2 but not IQ3 of MyoC. IQ3 contains a proline residue that may render it nonfunctional. Each long-tailed Dictyostelium myosin-I has now been shown to have a unique light chain (MyoB-MlcB, MyoC-MlcC, and MyoD-MlcD), whereas the short-tailed myosins-I, MyoA and MyoE, have the multifunctional calmodulin as a light chain. The diversity in light chain composition is likely to contribute to the distinct cellular functions of each myosin-I isozyme.
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Affiliation(s)
- Scott W Crawley
- Department of Biochemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6
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14
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Caride AJ, Bennett RD, Strehler EE. Kinetic analysis reveals differences in the binding mechanism of calmodulin and calmodulin-like protein to the IQ motifs of myosin-10. Biochemistry 2010; 49:8105-16. [PMID: 20731332 DOI: 10.1021/bi100644q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Myo10 is an unconventional myosin with important functions in filopodial motility, cell migration, and cell adhesion. The neck region of Myo10 contains three IQ motifs that bind calmodulin (CaM) or the tissue-restricted calmodulin-like protein (CLP) as light chains. However, little is known about the mechanism of light chain binding to the IQ motifs in Myo10. Binding of CaM and CLP to each IQ motif was assessed by nondenaturing gel electrophoresis and by stopped-flow experiments using fluorescence-labeled CaM and CLP. Although the binding kinetics are different in each case, there are similarities in the mechanism of binding of CaM and CLP to IQ1 and IQ2: for both IQ motifs Ca(2+) increased the binding affinity, mainly by increasing the rate of the forward steps. The general kinetic mechanism comprises a two-step process, which in some cases may involve the binding of a second IQ motif with lower affinity. For IQ3, however, the kinetics of CaM binding is very different from that of CLP. In both cases, binding in the absence of Ca(2+) is poor, and addition of Ca(2+) decreases the K(d) to below 10 nM. However, while the CaM binding kinetics are complex and best fitted by a multistep model, binding of CLP is fitted by a relatively simple two-step model. The results show that, in keeping with growing structural evidence, complexes between CaM or CaM-like myosin light chains and IQ motifs are highly diverse and depend on the specific sequence of the particular IQ motif as well as the light chain.
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Affiliation(s)
- Ariel J Caride
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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15
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De Nicola GF, Martin S, Bullard B, Pastore A. Solution structure of the Apo C-terminal domain of the Lethocerus F1 troponin C isoform. Biochemistry 2010; 49:1719-26. [PMID: 20104876 PMCID: PMC3388720 DOI: 10.1021/bi902094w] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 01/24/2010] [Indexed: 11/28/2022]
Abstract
Muscle contraction is activated by two distinct mechanisms. One depends on the calcium influx, and the other is calcium-independent and activated by mechanical stress. A prototypical example of stretch activation is observed in insect muscles. In Lethocerus, a model system ideally suited for studying stretch activation, the two mechanisms seem to be under the control of different isoforms of troponin C (TnC), F1 and F2, which are responsible for stretch and calcium-dependent regulation, respectively. We have previously shown that F1 TnC is a typical collapsed dumbbell EF-hand protein that accommodates one calcium ion in its fourth EF-hand. When calcium loaded, the C-terminal domain of F1 TnC is in an open conformation which allows binding to troponin I. We have determined the solution structure of the isolated F1 TnC C-terminal domain in the absence of calcium and have compared it together with its dynamical properties with those of the calcium-loaded form. The domain is folded also in the absence of calcium and is in a closed conformation. Binding of a single calcium is sufficient to induce a modest but clear closed-to-open conformational transition and releases the conformational entropy observed in the calcium-free form. These results provide the first example of a TnC domain in which the presence of only one calcium ion is sufficient to induce a closed-to-open transition and clarify the role of calcium in stretch activation.
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Affiliation(s)
- Gian Felice De Nicola
- Molecular Structure Division, National Institute for Medical Research, MRC, The Ridgeway, Mill Hill, London NW71AA, U.K
| | - Stephen Martin
- Molecular Structure Division, National Institute for Medical Research, MRC, The Ridgeway, Mill Hill, London NW71AA, U.K
| | - Belinda Bullard
- Department of Biology, University of York, York YO10 5DD, U.K
| | - Annalisa Pastore
- Molecular Structure Division, National Institute for Medical Research, MRC, The Ridgeway, Mill Hill, London NW71AA, U.K
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16
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The globular tail domain puts on the brake to stop the ATPase cycle of myosin Va. Proc Natl Acad Sci U S A 2008; 105:1140-5. [PMID: 18216256 DOI: 10.1073/pnas.0709741105] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Myosin Va is a well known processive motor involved in transport of organelles. A tail-inhibition model is generally accepted for the regulation of myosin Va: inhibited myosin Va is in a folded conformation such that the tail domain interacts with and inhibits myosin Va motor activity. Recent studies indicate that it is the C-terminal globular tail domain (GTD) that directly inhibits the motor activity of myosin Va. In the present study, we identified a conserved acidic residue in the motor domain (Asp-136) and two conserved basic residues in the GTD (Lys-1706 and Lys-1779) as critical residues for this regulation. Alanine mutations of these conserved charged residues not only abolished the inhibition of motor activity by the GTD but also prevented myosin Va from forming a folded conformation. We propose that Asp-136 forms ionic interactions with Lys-1706 and Lys-1779. This assignment locates the GTD-binding site in a pocket of the motor domain, formed by the N-terminal domain, converter, and the calmodulin in the first IQ motif. We propose that binding of the GTD to the motor domain prevents the movement of the converter/lever arm during ATP hydrolysis cycle, thus inhibiting the chemical cycle of the motor domain.
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17
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18
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Abstract
The elementary steps in complex biochemical reaction schemes (isomerization, dissociation, and association reactions) ultimately determine how fast any system can react in responding to incoming signals and in adapting to new conditions. Many of these steps have associated rate constants that result in subsecond responses to incoming signals or externally applied changes. This chapter is concerned with the techniques that have been developed to study such rapidly reacting systems in vitro and to determine the values of the rate constants for the individual steps. We focus principally on two classes of techniques: (1) flow techniques, in which two solutions are mixed within a few milliseconds and the ensuing reaction monitored over milliseconds to seconds, and (2) relaxation techniques, in which a small perturbation to an existing equilibrium is applied within a few microseconds and the response of the system is followed over microseconds to hundreds of milliseconds. These reactions are most conveniently monitored by recording the change in some optical signal, such as absorbance or fluorescence. We discuss the instrumentation that is (commercially) available to study fast reactions and describe a number of optical probes (chromophores) that can be used to monitor the changes. We discuss the experimental design appropriate for the different experimental techniques and reaction mechanisms, as well as the fundamental theoretical concepts behind the analysis of the data obtained.
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Affiliation(s)
- John F Eccleston
- Division of Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
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19
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De Nicola G, Burkart C, Qiu F, Agianian B, Labeit S, Martin S, Bullard B, Pastore A. The Structure of Lethocerus Troponin C: Insights into the Mechanism of Stretch Activation in Muscles. Structure 2007; 15:813-24. [PMID: 17637342 DOI: 10.1016/j.str.2007.05.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Revised: 05/07/2007] [Accepted: 05/07/2007] [Indexed: 10/23/2022]
Abstract
To gain a molecular description of how muscles can be activated by mechanical stretch, we have solved the structure of the calcium-loaded F1 isoform of troponin C (TnC) from Lethocerus and characterized its interactions with troponin I (TnI). We show that the presence of only one calcium cation in the fourth EF hand motif is sufficient to induce an open conformation in the C-terminal lobe of F1 TnC, in contrast with what is observed in vertebrate muscle. This lobe interacts in a calcium-independent way both with the N terminus of TnI and, with lower affinity, with a region of TnI equivalent to the switch and inhibitory peptides of vertebrate muscles. Using both synthetic peptides and recombinant proteins, we show that the N lobe of F1 TnC is not engaged in interactions with TnI, excluding a regulatory role of this domain. These findings provide insights into mechanically stimulated muscle contraction.
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Affiliation(s)
- Gianfelice De Nicola
- Molecular Structure Division, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
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20
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Pennestri M, Melino S, Contessa GM, Casavola EC, Paci M, Ragnini-Wilson A, Cicero DO. Structural basis for the interaction of the myosin light chain Mlc1p with the myosin V Myo2p IQ motifs. J Biol Chem 2006; 282:667-79. [PMID: 17074768 DOI: 10.1074/jbc.m607016200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calmodulin, regulatory, and essential myosin light chain are evolutionary conserved proteins that, by binding to IQ motifs of target proteins, regulate essential intracellular processes among which are efficiency of secretory vesicles release at synapsis, intracellular signaling, and regulation of cell division. The yeast Saccharomyces cerevisiae calmodulin Cmd1 and the essential myosin light chain Mlc1p share the ability to interact with the class V myosin Myo2p and Myo4 and the class II myosin Myo1p. These myosins are required for vesicle, organelle, and mRNA transport, spindle orientation, and cytokinesis. We have used the budding yeast model system to study how calmodulin and essential myosin light chain selectively regulate class V myosin function. NMR structural analysis of uncomplexed Mlc1p and interaction studies with the first three IQ motifs of Myo2p show that the structural similarities between Mlc1p and the other members of the EF-hand superfamily of calmodulin-like proteins are mainly restricted to the C-lobe of these proteins. The N-lobe of Mlc1p presents a significantly compact and stable structure that is maintained both in the free and complexed states. The Mlc1p N-lobe interacts with the IQ motif in a manner that is regulated both by the IQ motifs sequence as well as by light chain structural features. These characteristic allows a distinctive interaction of Mlc1p with the first IQ motif of Myo2p when compared with calmodulin. This finding gives us a novel view of how calmodulin and essential light chain, through a differential binding to IQ1 of class V myosin motor, regulate this activity during vegetative growth and cytokinesis.
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Affiliation(s)
- Matteo Pennestri
- Department of Chemical Science and Technology, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy
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21
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Musi V, Birdsall B, Fernandez-Ballester G, Guerrini R, Salvatori S, Serrano L, Pastore A. New approaches to high-throughput structure characterization of SH3 complexes: the example of Myosin-3 and Myosin-5 SH3 domains from S. cerevisiae. Protein Sci 2006; 15:795-807. [PMID: 16600966 PMCID: PMC2242487 DOI: 10.1110/ps.051785506] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
SH3 domains are small protein modules that are involved in protein-protein interactions in several essential metabolic pathways. The availability of the complete genome and the limited number of clearly identifiable SH3 domains make the yeast Saccharomyces cerevisae an ideal proteomic-based model system to investigate the structural rules dictating the SH3-mediated protein interactions and to develop new tools to assist these studies. In the present work, we have determined the solution structure of the SH3 domain from Myo3 and modeled by homology that of the highly homologous Myo5, two myosins implicated in actin polymerization. We have then implemented an integrated approach that makes use of experimental and computational methods to characterize their binding properties. While accommodating their targets in the classical groove, the two domains have selectivity in both orientation and sequence specificity of the target peptides. From our study, we propose a consensus sequence that may provide a useful guideline to identify new natural partners and suggest a strategy of more general applicability that may be of use in other structural proteomic studies.
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Affiliation(s)
- Valeria Musi
- National Institute for Medical Research, London NW71AA, United Kingdom
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22
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Ganoth A, Nachliel E, Friedman R, Gutman M. Molecular dynamics study of a calmodulin-like protein with an IQ peptide: spontaneous refolding of the protein around the peptide. Proteins 2006; 64:133-46. [PMID: 16568447 DOI: 10.1002/prot.20956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The Calmodulin (CaM) is a small (16.7 kDa), highly acidic protein that is crucial to all eukaryotes by serving as a prototypical calcium sensor. In the present study, we investigated, through molecular dynamics simulations, the dynamics of a complex between the Mlc1p protein, which is a CaM-like protein, and the IQ4 peptide. This protein-peptide interaction is of high importance because IQ motifs are widely distributed among different kinds of CaM-binding proteins. The Mlc1p-IQ4 complex, which had been resolved by crystallography to 2.1 A, confers to a Ca(+2)-independent stable structure. During the simulations, the complex undergoes a complicated modulation process, which involves bending of the angles between the alpha-helices of the protein, breaking of the alpha-helical structure of the IQ4 peptide into two sections, and formation of new contact points between the protein and the peptide. The dynamics of the process consist of fast sub picosecond events and much slower ones that take a few nanoseconds to completion. Our study expands the information embedded in the crystal structure of the Mlc1p-IQ4 complex by describing its dynamic behavior as it evolves from the crystal structure to a form stable in solution. The article shows that careful application of molecular dynamics simulations can be used for extending the structural information presented by the crystal structure, thereby revealing the dynamic configuration of the protein in its physiological environment.
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Affiliation(s)
- Assaf Ganoth
- Laser Laboratory for Fast Reactions in Biology, Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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23
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Ganoth A, Friedman R, Nachliel E, Gutman M. A molecular dynamics study and free energy analysis of complexes between the Mlc1p protein and two IQ motif peptides. Biophys J 2006; 91:2436-50. [PMID: 16844751 PMCID: PMC1562369 DOI: 10.1529/biophysj.106.085399] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Mlc1p protein from the budding yeast Saccharomyces cerevisiae is a Calmodulin-like protein, which interacts with IQ-motif peptides located at the yeast's myosin neck. In this study, we report a molecular dynamics study of the Mlc1p-IQ2 protein-peptide complex, starting with its crystal structure, and investigate its dynamics in an aqueous solution. The results are compared with those obtained by a previous study, where we followed the solution structure of the Mlc1p-IQ4 protein-peptide complex by molecular dynamics simulations. After the simulations, we performed an interaction free-energy analysis using the molecular mechanics Poisson-Boltzmann surface area approach. Based on the dynamics of the Mlc1p-IQ protein-peptide complexes, the structure of the light-chain-binding domain of myosin V from the yeast S. cerevisiae is discussed.
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Affiliation(s)
- Assaf Ganoth
- Laser Laboratory for Fast Reactions in Biology, Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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24
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Frank DJ, Martin SR, Gruender BNT, Lee YSR, Simonette RA, Bayley PM, Miller KG, Beckingham KM. Androcam is a tissue-specific light chain for myosin VI in the Drosophila testis. J Biol Chem 2006; 281:24728-36. [PMID: 16790438 DOI: 10.1074/jbc.m602094200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myosin VI, a ubiquitously expressed unconventional myosin, has roles in a broad array of biological processes. Unusual for this motor family, myosin VI moves toward the minus (pointed) end of actin filaments. Myosin VI has two light chain binding sites that can both bind calmodulin (CaM). However unconventional myosins could use tissue-specific light chains to modify their activity. In the Drosophila testis, myosin VI is important for maintenance of moving actin structures, called actin cones, which mediate spermatid individualization. A CaM-related protein, Androcam (Acam), is abundantly expressed in the testis and like myosin VI, accumulates on these cones. We have investigated the possibility that Acam is a testis-specific light chain of Drosophila myosin VI. We find that Acam and myosin VI precisely colocalize at the leading edge of the actin cones and that myosin VI is necessary for this Acam localization. Further, myosin VI and Acam co-immunoprecipitate from the testis and interact in yeast two-hybrid assays. Finally Acam binds with high affinity to peptide versions of both myosin VI light chain binding sites. In contrast, although Drosophila CaM also shows high affinity interactions with these peptides, we cannot detect a CaM/myosin VI interaction in the testis. We conclude that Acam and not CaM acts as a myosin VI light chain in the Drosophila testis and hypothesize that it may alter the regulation of myosin VI in this tissue.
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Affiliation(s)
- Deborah J Frank
- Department of Biology, Washington University, St. Louis, Missouri 63130, USA
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25
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Crawley SW, de la Roche MA, Lee SF, Li Z, Chitayat S, Smith SP, Côté GP. Identification and characterization of an 8-kDa light chain associated with Dictyostelium discoideum MyoB, a class I myosin. J Biol Chem 2006; 281:6307-15. [PMID: 16415352 DOI: 10.1074/jbc.m508670200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dictyostelium discoideum MyoB is a single-headed class I myosin. Analysis of purified MyoB by SDS-PAGE indicated the presence of an approximately 9-kDa light chain. A tryptic digest of MyoB yielded a partial sequence for the light chain that exactly matched a sequence in a 73-amino acid, 8,296-Da protein (dictyBase number DDB0188713). This protein, termed MlcB, contains two EF-hand motifs and shares approximately 30% sequence identity with the N- and C-terminal lobes of calmodulin. FLAG-MlcB expressed in Dictyostelium co-immunoprecipitated with MyoB but not with the related class myosins and MyoD. Recombinant MlcB bound Ca2+ with a Kd value of 0.2 microm and underwent a Ca2+-induced change in conformation that increased alpha-helical content and surface hydrophobicity. Mutational analysis showed that the first EF-hand was responsible for Ca2+ binding. In the presence and absence of Ca2+ MlcB was a monomer in solution and bound to a MyoB IQ motif peptide with a Kd value of approximately 0.5 microm. A MyoB head-neck construct with a Ser to Glu mutation at the TEDS site bound MlcB and displayed an actin-activated Mg2+ ATPase activity that was insensitive to Ca2+. We conclude that MlcB represents a novel type of small myosin light chain that binds to IQ motifs in a manner comparable with a single lobe of a typical four-EF-hand protein.
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Affiliation(s)
- Scott W Crawley
- Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada
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26
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Debreczeni JE, Farkas L, Harmat V, Hetényi C, Hajdú I, Závodszky P, Kohama K, Nyitray L. Structural Evidence for Non-canonical Binding of Ca2+ to a Canonical EF-hand of a Conventional Myosin. J Biol Chem 2005; 280:41458-64. [PMID: 16227209 DOI: 10.1074/jbc.m506315200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously identified a single inhibitory Ca2+-binding site in the first EF-hand of the essential light chain of Physarum conventional myosin (Farkas, L., Malnasi-Csizmadia, A., Nakamura, A., Kohama, K., and Nyitray, L. (2003) J. Biol. Chem. 278, 27399-27405). As a general rule, conformation of the EF-hand-containing domains in the calmodulin family is "closed" in the absence and "open" in the presence of bound cations; a notable exception is the unusual Ca2+-bound closed domain in the essential light chain of the Ca2+-activated scallop muscle myosin. Here we have reported the 1.8 A resolution structure of the regulatory domain (RD) of Physarum myosin II in which Ca2+ is bound to a canonical EF-hand that is also in a closed state. The 12th position of the EF-hand loop, which normally provides a bidentate ligand for Ca2+ in the open state, is too far in the structure to participate in coordination of the ion. The structure includes a second Ca2+ that only mediates crystal contacts. To reveal the mechanism behind the regulatory effect of Ca2+, we compared conformational flexibilities of the liganded and unliganded RD. Our working hypothesis, i.e. the modulatory effect of Ca2+ on conformational flexibility of RD, is in line with the observed suppression of hydrogen-deuterium exchange rate in the Ca2+-bound form, as well as with results of molecular dynamics calculations. Based on this evidence, we concluded that Ca2+-induced change in structural dynamics of RD is a major factor in Ca2+-mediated regulation of Physarum myosin II activity.
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Affiliation(s)
- Judit E Debreczeni
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
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27
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Green JL, Martin SR, Fielden J, Ksagoni A, Grainger M, Yim Lim BYS, Molloy JE, Holder AA. The MTIP-myosin A complex in blood stage malaria parasites. J Mol Biol 2005; 355:933-41. [PMID: 16337961 DOI: 10.1016/j.jmb.2005.11.027] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2005] [Revised: 11/04/2005] [Accepted: 11/09/2005] [Indexed: 10/25/2022]
Abstract
Parasites of the Apicomplexa phylum use an actomyosin motor to drive invasion of host cells. The motor complex is located at the parasite's periphery between the plasma membrane and an inner membrane complex. A crucial component of this complex is myosin tail domain interacting protein (MTIP) identified in the murine malaria parasite Plasmodium yoelii. Here, we show that MTIP is expressed in Plasmodium falciparum merozoites, localises to the periphery of the cell and is present in a complex with myosin A. The MTIP-myosin A tail interaction has a Kd of 235 nM and calcium ions do not play a role in modulating the binding affinity of the two molecules, despite reports of a predicted EF-hand in MTIP. Antibodies to MTIP were used to immobilise the MTIP-myosin A complex, allowing actin binding and motility to be examined. Measurement of actin filament velocities powered by myosin A revealed a velocity of 3.51 microm s(-1), a speed comparable to fast muscle myosins. A short peptide derived from the tail of myosin A (C-MyoA) bound to MTIP and was able to disrupt the association of MTIP and myosin A in parasite lysates. C-MyoA peptidomimetic compounds that disrupt the MTIP-myosin A interaction are predicted to inhibit parasite motility and host cell invasion, which may be targets for new therapeutic approaches.
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Affiliation(s)
- Judith L Green
- Division of Parasitology, MRC National Institute for Medical Research, London NW7 1AA, UK.
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28
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Kouprina N, Pavlicek A, Collins NK, Nakano M, Noskov VN, Ohzeki JI, Mochida GH, Risinger JI, Goldsmith P, Gunsior M, Solomon G, Gersch W, Kim JH, Barrett JC, Walsh CA, Jurka J, Masumoto H, Larionov V. The microcephaly ASPM gene is expressed in proliferating tissues and encodes for a mitotic spindle protein. Hum Mol Genet 2005; 14:2155-65. [PMID: 15972725 DOI: 10.1093/hmg/ddi220] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The most common cause of primary autosomal recessive microcephaly (MCPH) appears to be mutations in the ASPM gene which is involved in the regulation of neurogenesis. The predicted gene product contains two putative N-terminal calponin-homology (CH) domains and a block of putative calmodulin-binding IQ domains common in actin binding cytoskeletal and signaling proteins. Previous studies in mouse suggest that ASPM is preferentially expressed in the developing brain. Our analyses reveal that ASPM is widely expressed in fetal and adult tissues and upregulated in malignant cells. Several alternatively spliced variants encoding putative ASPM isoforms with different numbers of IQ motifs were identified. The major ASPM transcript contains 81 IQ domains, most of which are organized into a higher order repeat (HOR) structure. Another prominent spliced form contains an in-frame deletion of exon 18 and encodes 14 IQ domains not organized into a HOR. This variant is conserved in mouse. Other spliced variants lacking both CH domains and a part of the IQ motifs were also detected, suggesting the existence of isoforms with potentially different functions. To elucidate the biochemical function of human ASPM, we developed peptide specific antibodies to the N- and C-termini of ASPM. In a western analysis of proteins from cultured human and mouse cells, the antibodies detected bands with mobilities corresponding to the predicted ASPM isoforms. Immunostaining of cultured human cells with antibodies revealed that ASPM is localized in the spindle poles during mitosis. This finding suggests that MCPH is the consequence of an impairment in mitotic spindle regulation in cortical progenitors due to mutations in ASPM.
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Affiliation(s)
- Natalay Kouprina
- Laboratory of Biosystems and Cancer, National Cancer Institute, Bethesda, MD 20892, USA
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29
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Wang B, Martin SR, Newman RA, Hamilton SL, Shea MA, Bayley PM, Beckingham KM. Biochemical properties of V91G calmodulin: A calmodulin point mutation that deregulates muscle contraction in Drosophila. Protein Sci 2005; 13:3285-97. [PMID: 15557269 PMCID: PMC2287309 DOI: 10.1110/ps.04928204] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
A mutation (Cam7) to the single endogenous calmodulin gene of Drosophila generates a mutant protein with valine 91 changed to glycine (V91G D-CaM). This mutation produces a unique pupal lethal phenotype distinct from that of a null mutation. Genetic studies indicate that the phenotype reflects deregulation of calcium fluxes within the larval muscles, leading to hypercontraction followed by muscle failure. We investigated the biochemical properties of V91G D-CaM. The effects of the mutation on free CaM are minor: Calcium binding, and overall secondary and tertiary structure are indistinguishable from those of wild type. A slight destabilization of the C-terminal domain is detectable in the calcium-free (apo-) form, and the calcium-bound (holo-) form has a somewhat lower surface hydrophobicity. These findings reinforce the indications from the in vivo work that interaction with a specific CaM target(s) underlies the mutant defects. In particular, defective regulation of ryanodine receptor (RyR) channels was indicated by genetic interaction analysis. Studies described here establish that the putative CaM binding region of the Drosophila RyR (D-RyR) binds wild-type D-CaM comparably to the equivalent CaM-RyR interactions seen for the mammalian skeletal muscle RyR channel isoform (RYR1). The V91G mutation weakens the interaction of both apo- and holo-D-CaM with this binding region, and decreases the enhancement of the calcium-binding affinity of CaM that is detectable in the presence of the RyR target peptide. The predicted functional consequences of these changes are consonant with the in vivo phenotype, and indicate that D-RyR is one, if not the major, target affected by the V91G mutation in CaM.
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Affiliation(s)
- Bo Wang
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251, USA
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30
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Martin SR, Biekofsky RR, Skinner MA, Guerrini R, Salvadori S, Feeney J, Bayley PM. Interaction of calmodulin with the phosphofructokinase target sequence. FEBS Lett 2005; 577:284-8. [PMID: 15527800 DOI: 10.1016/j.febslet.2004.10.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2004] [Accepted: 10/04/2004] [Indexed: 11/28/2022]
Abstract
Ca4.calmodulin (Ca4.CaM) inhibits the glycolytic enzyme phosphofructokinase, by preventing formation of its active tetramer. Fluorescence titrations show that the affinity of complex formation of Ca4.CaM with the key 21-residue target peptide increases 1000-fold from pH 9.0 to 4.8, suggesting the involvement of histidine and carboxylic acid residues. 1H NMR pH titration indicates a marked increase in pKa of the peptide histidine on complex formation and HSQC spectra show related pH-dependent changes in the conformation of the complex. This unusually strong sensitivity of a CaM-target complex to pH suggests a potential functional role for Ca4.CaM in regulation of the glycolytic pathway.
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Affiliation(s)
- Stephen R Martin
- Division of Physical Biochemistry, National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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31
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Nguyen H, Higuchi H. Motility of myosin V regulated by the dissociation of single calmodulin. Nat Struct Mol Biol 2005; 12:127-32. [PMID: 15665867 DOI: 10.1038/nsmb894] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Accepted: 12/16/2004] [Indexed: 11/09/2022]
Abstract
Myosin V is a calmodulin-binding motor protein. The dissociation of single calmodulin molecules from individual myosin V molecules at 1 microM Ca(2+) correlates with a reduction in sliding velocity in an in vitro motility assay. The dissociation of two calmodulin molecules at 5 microM Ca(2+) correlates with a detachment of actin filaments from myosin V. To mimic the regulation of myosin V motility by Ca(2+) in a cell, caged Ca(2+) coupled with a UV flash system was used to produce Ca(2+) transients. During the Ca(2+) transient, myosin V goes through the functional cycle of reduced sliding velocity, actin detachment and reattachment followed by the recovery of the sliding velocity. These results indicate that myosin V motility is regulated by Ca(2+) through a reduction in actin-binding affinity resulting from the dissociation of single calmodulin molecules.
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Affiliation(s)
- HoaAnh Nguyen
- Center for Interdisciplinary Research, Tohoku University, Sendai 980-8578, Japan
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32
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Martin SR, Bayley PM. Calmodulin bridging of IQ motifs in myosin-V. FEBS Lett 2004; 567:166-70. [PMID: 15178316 DOI: 10.1016/j.febslet.2004.04.053] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Revised: 04/14/2004] [Accepted: 04/23/2004] [Indexed: 11/18/2022]
Abstract
Ca(2+)-saturated calmodulin binds to double-length IQ lever-arm sequences from murine myosin-V, forming a 1:1 "bridging" complex with very high affinity, (K9d)<10 pM for double motifs, IQ34, IQ45 and IQ56). Such a 1:1 complex involves interaction of one calmodulin (CaM) molecule with two adjacent IQ-motifs, providing a molecular mechanism for the observed Ca(2+)-dependent CaM dissociation from the IQ-region. Structural considerations suggest that formation of the 1:1 complex requires a severe distortion of the lever-arm, potentially regulating functional motility. This would be consistent with a recent report of diverse, irregular shapes of the lever arm of myosin-V induced by the presence of Ca(2+).
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Affiliation(s)
- Stephen R Martin
- Division of Physical Biochemistry, National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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33
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Abstract
All characterized myosins share a common ATPase mechanism. However, detailed kinetic analyses suggest that modulation of the rate and equilibrium constants that define the ATPase cycle confers specific properties to these motor proteins, suiting them to specific physiological tasks. Understanding the kinetic mechanisms allows potential cellular functions of the different myosin classes and isoforms to be better defined.
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Affiliation(s)
- Enrique M De La Cruz
- Department of Molecular Biophysics and Biochemistry, Yale University, PO Box 208114, New Haven, CT 06520, USA
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34
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Farkas L, Malnasi-Csizmadia A, Nakamura A, Kohama K, Nyitray L. Localization and characterization of the inhibitory Ca2+-binding site of Physarum polycephalum myosin II. J Biol Chem 2003; 278:27399-405. [PMID: 12754206 DOI: 10.1074/jbc.m304220200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A myosin II is thought to be the driving force of the fast cytoplasmic streaming in the plasmodium of Physarum polycephalum. This regulated myosin, unique among conventional myosins, is inhibited by direct Ca2+ binding. Here we report that Ca2+ binds to the first EF-hand of the essential light chain (ELC) subunit of Physarum myosin. Flow dialysis experiments of wild-type and mutant light chains and the regulatory domain revealed a single binding site that shows moderate specificity for Ca2+. The regulatory light chain, in contrast to regulatory light chains of higher eukaryotes, is unable to bind divalent cations. Although the Ca2+-binding loop of ELC has a canonical sequence, replacement of glutamic acid to alanine in the -z coordinating position only slightly decreased the Ca2+ affinity of the site, suggesting that the Ca2+ coordination is different from classical EF-hands; namely, the specific "closed-to-open" conformational transition does not occur in the ELC in response to Ca2+. Ca2+- and Mg2+-dependent conformational changes in the microenvironment of the binding site were detected by fluorescence experiments. Transient kinetic experiments showed that the displacement of Mg2+ by Ca2+ is faster than the change in direction of cytoplasmic streaming; therefore, we conclude that Ca2+ inhibition could operate in physiological conditions. By comparing the Physarum Ca2+ site with the well studied Ca2+ switch of scallop myosin, we surmise that despite the opposite effect of Ca2+ binding on the motor activity, the two conventional myosins could have a common structural basis for Ca2+ regulation.
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Affiliation(s)
- Laszlo Farkas
- Department of Biochemistry, Eötvös Loránd University, Budapest 1117, Hungary
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35
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Bayley P, Martin S, Browne P, Royer C. Time-resolved fluorescence anisotropy studies show domain-specific interactions of calmodulin with IQ target sequences of myosin V. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2003; 32:122-7. [PMID: 12734700 DOI: 10.1007/s00249-002-0274-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Single cysteine mutants of calmodulin, Cam(S38C) and Cam(N111C), have been specifically labelled with Alexa488 maleimide to study the effects of calcium on the structural dynamics of calmodulin complexed with IQ3, IQ4 and IQ34 target peptide motifs of mouse unconventional myosin-V. Using phase fluorometry, the time-resolved anisotropy shows well-separated global and segmental correlation times. The calcium-sensitive global motion of either calmodulin domain can be independently monitored in domain-specific interactions of either apo- or Ca(4).calmodulin with IQ3 or IQ4 peptides. C-domain interactions predominate, and apo-N-domain interactions are unexpectedly weak. The 1:1 complex of Ca(4).calmodulin with IQ34 behaves as a compact globular species. The results demonstrate novel dynamic aspects of calmodulin-IQ interactions relating to the calcium regulation of motility of unconventional myosin.
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Affiliation(s)
- Peter Bayley
- Division of Physical Biochemistry, National Institute for Medical Research, Mill Hill, London, NW7 1AA, UK.
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